Characterizing the interplay between galactic star formation and ionization feedback with PRIMA

Recent results from the James Webb Space Telescope show that nearby spiral galaxies are dominated by the presence of H i and H ii bubbles that strongly shape their surrounding medium. These bubbles result from the feedback of high-mass stars at different stages of their life cycle. However, early (pre-supernova) feedback from high-mass stars is still poorly quantified. Recent results from numerical simulations suggest that the impact of high-mass star early feedback (photoionization, wind) on star formation properties is complex, time-dependent, and strongly depends on physical conditions, including the magnetic field properties. In our Galaxy, ionized (H ii) regions observed in different evolution stages show a high diversity of star formation in their associated photo-dissociation regions (PDRs). However, the way in which the low- to high-density interstellar medium evolves to this situation remains elusive. Quantifying the impact of early feedback from high-mass stars on star formation properties and star formation laws (star formation rate, star formation efficiency versus gas surface density,

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gas) will allow for a better understanding of the evolution of star formation laws in external galaxies, the laws that are key ingredients of galaxy evolution models. PRIMA, with its high sensitivity, large mapping efficiency, and polarimetric capabilities, offers a unique opportunity to address the way radiative feedback and magnetic field control star formation in the Milky Way.